The proposed work deals with control of ion and water content in red blood cells. Permeability and transport processes will be studied, with particular reference to their interactions with cellular metabolism. Pathological processes involving Heinz bodies and formaldehyde damage to red blood cells will be studied. A comparative approach, utilizing red blood cells from several species is planned. BIBLIOGRAPHIC REFERENCES: Koller, C.A., Orringer, E.P., Parker, J.C.: Mechanism of cation and water loss in pyruvate kinase deficient red blood cells under anoxic condition. Clin. Res. 24: 313A, 1976. Parker, J.C., Orringer, E.P., McManus, T.J.: Disorders of ion transport in red blood cells. In The Physiological Basis for Disorders of Biomembranes. (Eds. Andreoli, T.E., Hoffman, J.F., Fanestil, D.D.). Plenum Press, 1977, (in press).